They all form the 2nd and 3rd person singular (you and he, she, it) with -ur.
Plus, eyjur means islands in Icelandic, so it’s a nifty pun.
ey-j-ur verbs are one of the smallest categories of verbs, with fewer than 40 members. They’re not terribly common, either, accounting for just 3% of all verbs used. Still, you should learn them one day, and since you stumbled on this article it seems today is that day!
A quick caveat on terminology: “ey-j-ur verbs” is just what I call this group because it feels more intuitive than the more academic notation. You might know this category as Weak 3 verbs, W3, or something similarly abstruse. I’ve also seen them called -ur verbs, which I like for its intuitive nature, but dislike for not really differentiating them from the strong verbs.
Rule of Thumb
The ey-j-ur verbs conjugate like regular strong verbs in the present tense. In the past tense, they conjugate like -i verbs, but with a strong-verb-like vowel shift.
These charts summarise the whole article: if they look like a lot, look at them again after reading. Everything will make sense after that.
These verbs aren't really all that interesting in the present tense: they work like perfectly regular strong verbs.
You might have noticed that the j from the -ja infinitive ending pops back up in the plural forms (við, þið, þeir, þær, þau) - sometimes. That’s because Icelandic spelling has some frankly convoluted rules about when to write j, which are beyond the scope of this article. Focus on the sound, not the spelling.
Now we’re talking! ey-j-ur verbs really shine in the past tense, because they combine:
the vowel shift of strong verbs, and
the suffix ending of -i verbs.
The vowel shift of ey-j-ur verbs actually isn’t quite the same as that of regular strong verbs. In fact, it’s almost like an inverse of the regular strong verb vowel shift.
The majority of these verbs have e in the stem, so that’s the most common one. Only a couple verbs have ý in the stem, so that’s the least important one.